My personal opinion is that there need to be clear rules for members and moderators to follow. They do not need to go down to the last detail, but they need to be unambiguous enough that everyone can know what to expect, and that it is ensured that at the very least, nobody will be banned without a proper reason for this.

Furthermore, I think moderation needs to be consistent. If someone states "a discussion about moderation is not permitted", but then only deletes those comments critical of his/her moderation and leaves those up which are supportive, then the moderation is not consistent. This would reveal that it is not the discussion about moderation that bothers the moderator, but the criticism. When you have a very large number of moderators and members, it is not easy to achieve consistency. Without clear rules and guidelines for members and moderators (what is offensive, when shall a post be edited/deleted, what are the prerequisites for a ban to go into effect, etc.), it gets harder and harder to ensure consistency and fairness the more members and moderators you have.

Regarding editing/deletion of posts, I do think that it should only be done if the post is actually offensive. I think threads should be locked when they get out of hand. But all that is up to the administrator of the board, it should just be consistent and fair - equal treatment for all. I have no problem with a very strict policy with quick bans, as long as it is clear for what and as long as the reasons for bans are not vague ("disruption of the forum", "spirit of the TOS"). They can be more vague if it is a small number of moderators as one will quickly learn what to expect from them, but they should be less and less vague, the more moderators there are.